The primary objectives of this renewal application are to establish the molecular mechanisms involve in heme transport in Neisseria gonorrhoea and to define the regulation of heme transport genes. The specific aims for the next five years are to: 1) Characterize the binding of heme to the outer membrane of gonococci and define the mechanism utilize for the transport of iron and/or heme across the outer membrane, 2) clone and characterize gonococcal gene encoding proteins involved in heme binding and transport, 3) construct gonococcal mutants defective in heme binding and transport, and 4) examine the regulation of heme binding and transport genes. The results obtained in these studies will enable Dr. Genco to elucidate the specific mechanisms employed for the transport of heme in gonococci. The ability of gonococci to transport heme will be correlated with the virulence potential of this sexually transmitted disease pathogen.